Explicit modeling of cone and strip footing penetration under drained and undrained conditions using a visco-hypoplastic model

In this paper a visco-hypoplastic model, which can describe viscous behavior including creep, relaxation and rate dependency of cohesive soils, is implemented in the form of a user subroutine VUMAT in Abaqus/Explicit to model soil-structure interaction in clayey soil. The VUMAT subroutine is verified with a UMAT subroutine by back-calculating standard element tests. In addition, an uncoupled analysis strategy, using effective parameters to calculate the stresses in nearly incompressible materials, is implemented in user subroutines to model the soil under undrained conditions. A strategy of scaling the reference creep rate is used to improve the efficiency of the explicit analyses. Furthermore, the penetration process of a cone penetration test (CPT) in a cohesive soil is simulated to investigate the effects of penetration velocity on the cone penetration resistance. Finally, the user subroutine VUMAT is used together with the coupled Eulerian-Lagrangian method to investigate a strip footing problem.